Can I hook up two amps to the same speaker?

don't run them straight in.
If you put a pair of dpdt(double pole, double throw) switches in between, and the center pole is the wires going to the speaker terminals, one side of the switches is one amp, the other sides the other. fine.

So I gather this cannot be done with quality speaker cable? We're talking about plain ole 16 guage speaker wire or the like? I wanted this for a hi end rig. I suppose it cannot be done with these double pole/throw switches with audiophool speaker cable? Is my thinking wrong? I have no idea what these switches are about. I am an electric doofus.

With respect to your question about wire -- yes, you can use high end wire with Elizabeth's switch idea. Most high end speaker wire comes terminated with spade lugs, so just make sure that the switch you buy can accommodate the size of spades on your wire.

Do you have an extra line level output on one of your amps and an extra line level input on the other? If so, you can connect them at the line level, assuming they are close enough together.